Programmatic risk analysis to search for life on Mars

NASA is facing the problem of choosing a strategy for the future exploration of Mars. Many scientists and members of the public are interested in knowing if life, in some form, exists or ever existed on the planet. The missions required to search for life are complex, and the probability of a clear discovery in the short term is small. Other objectives of the current Mars program are to pave the way for future human exploration and to shed some light on the evolution of the Earth by studying the geologic and climatic history of Mars. To support the choice of a planetary exploration program, we describe in this paper an analytical framework that quantifies a mission's failure risks as well as its benefits. The model permits optimal budget allocation (beyond a minimum amount) among investments that increase the reliability of the technical system, initial budget reserves needed to resolve potential development problems, and additional investments in the scientific capabilities of the spacecraft. This optimal allocation is based on the maximization of the expected value of a valuation function that represents the preferences of the NASA managers, the scientists and the public. For these different groups, the valuation function captures and integrates tradeoffs among technical failure risks, management failure risks, and the mission's scientific benefits.